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Introduction to Cells & Organelles

Introduction to Cells & Organelles. Introduction to Cells…. The Cell Theory: 1. All living organisms are made up of cells 2. Cells are the basic structural & functional unit of life Cell properties directly relate to the properties of life 3. New cells arise from pre-existing cells

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Introduction to Cells & Organelles

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  1. Introduction to Cells & Organelles

  2. Introduction to Cells… • The Cell Theory: • 1. All living organisms are made up of cells • 2. Cells are the basic structural & functional unit of life • Cell properties directly relate to the properties of life • 3. New cells arise from pre-existing cells • All cells come from the reproduction of existing cells

  3. Characteristics of Cells • Cell Characteristics: • Vary in size, shape & function • Composed of same basic parts & have some common functions • Common structures: • Plasma (cell) membrane: • Thin, flexible membrane that surrounds the cell • Cytoplasm: • Fluid material inside the cell that houses the cells organelles • Nucleus: • Control center of the cell – contains the genetic information

  4. Variations in Cells • All living organisms are made of cells but they may vary: • Unicellular organisms: • Composed of one cell • Multi-cellular organisms: • Composed of many cells that may be organized into tissues • Prokaryotes vs. Eukaryotes: • Prokaryotes: • Lack (don’t have) membrane-bound organelles • Don’t have a nucleus • Simple organisms: ex: bacteria • Eukaryotes: • Have membrane-bound organelles • Have a nucleus • Complex organisms: ex: plants, animals, fungi

  5. Organelles • Cellular organelles: • Plasma (Cell) Membrane: • Defines exterior of cell • Separates living cell from non-living surroundings • Separates intracellular and extracellular fluids • Controls what enters & leaves the cell • Maintains homeostasis • Selectively permeable • “chooses” what enters & leaves the cell

  6. Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Plasma Membrane • PM is said to be “fluid “= it moves

  7. Organelles cont. • Cell Wall: • Found in plants only – nonliving layer • Lies immediately against the cell wall (outside cell membrane) • Pushes against the cell wall = helps maintain cell shape • Made of cellulose • Protects, gives shape, & prevents excess water uptake in cells Cell Wall

  8. Organelles Cont. • Cytoplasm: • Jelly-like substance enclosed by cell membrane • Provides medium for chemical reactions • Contains organelles • Made of water & dissolved solutes Cytoplasm

  9. Organelles cont. • Nucleus: • Controls cellular activities • Contains genetic information (genes = DNA = control characteristics) • Usually located in the center of the cell • Nucleolus: • Inside nucleus • Spherical shape & highly visible • Makes ribosome's & proteins Nucleus Nucleolus

  10. Organelles Cont. • Nuclear Membrane (envelope): • Double membrane that surrounds nucleus • Nuclear pores = controls what enters & leaves the nucleus • Connected to the Rough ER Nuclear Pores

  11. Organelles Cont. • Ribosomes: • Made up of proteins & RNA • Make proteins = “protein factories” = join amino acids to make proteins (process = protein synthesis) • Attached to the ER = Rough ER or • Free within the cytoplasm

  12. Organelles Cont. • Endoplasmic Reticulum (ER): • Site of chemical reactions • 2 types: • Smooth ER (SER): • Lacks ribosomes • Makes/synthesizes lipids, steroids, & hormones • Typically found connected to the Rough ER • Rough ER (RER): • Ribosomes located on its surface • Makes & exports proteins & proteins for the plasma membrane • Hint: involved with making proteins because of ribosomes • Typically found connected to the nucleus

  13. Organelles Cont. • Golgi Bodies: • Made of stacks of flattened membranes • Receive proteins made by ER • Transports (in vesicles) proteins • Function: modify, sort, package, transport, and secrete proteins

  14. Organelles Cont. • Mitochondria: • Transforms energy • “powerhouse” of the cell – create ATP • Contains its own DNA & contains ribosomes • Mitochondrial DNA is inherited from mother • Found in all eukaryotic cells

  15. Organelles Cont. • Lysosomes: • Lyse: to burst • Small & round digestive structure – contain digestive materials/enzymes • Breaks down (digests) food, bacteria, and worn out cell parts LysosomesAnimation Video

  16. Organelles Cont. • Vacuoles: • Fluid filled sacs that are used for storage • Smaller & not as prevalent in animal cells • Large & prevalent organelle in plant cells • Storage of water, nutrients, enzymes, wastes, and chemical defenses

  17. Organelles Cont. • Chloroplasts: • Found in plant cells & contain chlorophyll • Site of photosynthesis • Photosynthesis: convert sunlight energy into glucose = produce food • Occurs in the chlorophyll that is stored in the thylakoids

  18. Organelles Cont. • Cytoskeleton: • Maintains cell shape • Help move organelles • Made of proteins Cytoskeleton

  19. Organelles Cont. • Centrioles: • Found in animal cells • Paired structures near nucleus that appear during cell division – help pull chromosome pairs apart

  20. Organelles Cont. • Cilia – • Occur in large numbers on cell surface • Hair-like structures that move substances over cells surface (respiratory tract) • Flagella – • Whip-like structure • Moves a cell (sperm cell & prokaryotes)

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